Governments have limited resources, in terms of defense budgets, and they will most likely spend on a threat that is real or looks real and not on a threat that looks a bit, well, wishy-washy.

Put it simply, the ROK MND will spend its money on weapons needed to fight the DPRK or China.
To the ROK, international humanitarian and disaster relief missions are second fiddle compared to the main mission of training for and fighting a possible war with the DPRK or China.

As for the Japanese, their military is already geared for international humanitarion missions and disaster relief, so expect incremental improvements, but not wholesale changes.